Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSPONTIAC2008GRAND PRIX BASEREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 226 (ENGINE COOLING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESENGINE OVERHEATING
2008 Pontiac Grand Prix Base
Engine Overheating
2008 Pontiac Grand Prix BaseSECTION Engine Overheating
WARNING: This page is about a different car, the 2007 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
Engine Overheating
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| DEFINITION: The engine temperature lamp comes on and stays on, the temperature gauge shows hot or coolant overflows from the coolant recovery reservoir onto the ground while the engine is running. | ||||
| 1 | Inspect for a loss of coolant. Has a loss of coolant occurred? |
- | Go to Step 2 | Go to Step 3 |
| 2 | Refer to Loss of Coolant . Does the engine still overheat? |
- | Go to Step 3 | System OK |
| 3 | Use J 24460-01
Cooling System Pressure Tester to test for a loss of system pressure. See Special Tools . Did you notice a loss of system pressure? |
- | Go to Step 4 | Go to Step 5 |
| 4 | Correct the system pressure. Does the engine still overheat? |
- | Go to Step 5 | System OK |
| 5 | Use J 23688
Coolant and Battery Fluid Tester or J 26568
Coolant and Battery Fluid Tester to test for low coolant protection. See Special Tools . Is the low coolant protection at or above the specified value? |
-37°C (-34°F) | Go to Step 7 | Go to Step 6 |
| 6 | Correct as necessary. Does the engine still overheat? |
- | Go to Step 7 | System OK |
| 7 | Test for an inoperative cooling fan. Refer to Cooling Fan Inoperative . Did you find any inoperative cooling fans? |
- | Go to Step 8 | Go to Step 9 |
| 8 | Repair or replace the electric cooling fans as necessary. Refer to Cooling Fan Motor Replacement - Electric (LS4) or Cooling Fan Motor Replacement - Electric (L26, L32) . Does the engine still overheat? |
- | Go to Step 9 | System OK |
| 9 |
|
- | Go to Step 11 | Go to Step 10 |
| 10 | Replace the drive belt tensioner. Refer to Drive Belt Tensioner Replacement
, or Drive Belt Tensioner Replacement - Accessory
. Does the engine still overheat? |
- | Go to Step 11 | System OK |
| 11 | Test the radiator fins for an obstruction. Are any of radiator fins obstructed? |
- | Go to Step 12 | Go to Step 13 |
| 12 |
|
- | Go to Step 13 | System OK |
| 13 | Inspect the cooling system passages. Are any of the cooling system passages blocked by rust or scale? |
- | Go to Step 14 | Go to Step 15 |
| 14 |
|
- | Go to Step 15 | System OK |
| 15 | Inspect for a pinched or kinked coolant recovery reservoir hose. Is the reservoir hose pinched or kinked? |
- | Go to Step 16 | Go to Step 17 |
| 16 | Replace or reroute the hose as necessary. Refer to Coolant Recovery Reservoir Replacement (LS4) or Coolant Recovery Reservoir Replacement (L26, L32) . Does the engine still overheat? |
- | Go to Step 17 | System OK |
| 17 | Inspect for a loose, damaged, and/or missing deflector. Are the deflectors loose, damaged, or missing? |
- | Go to Step 18 | Go to Step 19 |
| 18 | Replace the deflectors. Refer to the following procedures:
Does the engine still overheat? |
- | Go to Step 19 | System OK |
| 19 | Inspect the thermostat. Is the thermostat stuck in the closed position? |
- | Go to Step 20 | Go to Step 21 |
| 20 | Replace the thermostat. Refer to Thermostat Replacement (LS4) or Thermostat Replacement (L26/L32) . Does the engine still overheat? |
- | Go to Step 21 | System OK |
| 21 | Test for a faulty water pump. Is the water pump faulty? |
- | Go to Step 22 | Go to Step 23 |
| 22 | Replace the water pump. Refer to Water Pump Replacement (LS4) or Water Pump Replacement (L26/L32) . Does the engine still overheat? |
- | Go to Step 23 | System OK |
| 23 | Check for an incorrect radiator. Is the radiator correct? |
- | Go to Step 1 | Go to Step 24 |
| 24 | Install the correct radiator. Refer to Radiator Replacement (LS4) or Radiator Replacement (L26, L32) . Does the engine still overheat? |
- | Go to Step 1 | System OK |
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.